System Sizer

Pro

Refrigeration system design: lines, pressure, cycle, and annual energy.

Overview

System Sizer covers a refrigeration system from line sizing through to annual energy. It sizes lines the way industrial designers do, by saturated-temperature penalty, velocity, oil return, and flash-gas margin, then checks the pipe mechanically to ASME B31.5, analyses the cycle, and models a full transcritical CO2 booster over 8,760 hours of weather. Eleven refrigerants are covered: R-717 (ammonia), R-744 (CO2) both subcritical and transcritical, the A2L family (R-32, R-454B, R-1234yf, R-1234ze(E), R-455A, R-454C), and legacy A1s.

Key features

• Eleven line duties: dry suction, discharge, liquid, hot-gas defrost, pumped liquid, wet suction return, plus five transcritical CO2 duties (gas cooler discharge and outlet, flash-gas bypass, liquid from receiver, transcritical defrost)
• ΔT saturation-penalty criterion with Darcy-Weisbach / Colebrook friction; supercritical lines use a ΔP budget instead, because above the critical point no saturation curve exists
• ASME B31.5 pressure design with CO2 circuit ratings: 120 bar high side, 60 bar receiver, 50 bar suction
• Lifetime warming (TEWI): direct refrigerant loss (charge × annual leak rate × GWP, plus end-of-life recovery) alongside indirect electricity emissions, so the refrigerant and energy halves of a decision are weighed together. It reports nothing at all without a system charge, because a TEWI with no charge is just the electricity term wearing a different name
• EPA eGRID subregion carbon factors: type a state or region and the grid CO2 factor follows it (Washington 0.267 lb/kWh against West Virginia’s 1.969), instead of one national average standing in for every project
• Refrigerant transition advisory: given the application and a date, whether a refrigerant stays permitted under the AIM Act phasedown, how much GWP headroom is left, and which alternatives qualify with their A2L consequences for charge limits, ventilation and detection
• Oil-return riser check at minimum part load, flash-gas guard on liquid lines, and Lockhart-Martinelli two-phase sizing for overfeed wet returns
• Transcritical CO2 boosters: parallel compression, vapour ejectors, heat recovery, and dry, adiabatic, or evaporative gas cooling, with the high-side pressure optimised for COP
• Pressure-enthalpy diagrams for both subcritical cycles and transcritical boosters, with supercritical isotherms and branch-aware mass fractions
• 8,760-hour annual energy comparing fixed against floating head pressure and, for CO2, fixed against floating optimal high-side pressure
• CO2-specific safety advisories: trapped-liquid isochoric pressure rise, and dry-ice formation near the triple point
• Full CO2 property surface through the supercritical region, plus CoolProp-derived saturation tables validated against published ASHRAE line-capacity data
• Results chain to Safety Systems, Vessel Sizer, and Charge Inventory automatically

How to use it

1. 1

   Click System Sizer on the RIME ribbon (Refrigeration panel).

2. 2

   Pick the refrigerant and line type, and enter load and operating temperatures.

3. 3

   Calculate. The smallest passing size is recommended with the full candidate table.

4. 4

   Use the Pressure tab for ASME B31.5 wall thickness, and the Cycle or CO2 System tab for performance.

5. 5

   On the CO2 System tab, load a weather file and run 8,760 hours to compare control strategies.